1. Field of the Invention
This invention relates to slip clutches for interposition between a rotary shaft and an element carried on the shaft such as a gear, cam, pulley or the like.
2. Description of the Prior Art
It has heretofore been common practice to mount elements, such as gears, cams, pulleys, cranks and the like on a shaft, the element or the shaft providing the power input if desired. The elements may be freely rotatable with respect to the shaft or may be held against rotation by a key or set screw.
It has also been common practice to hold the element against longitudinal movement lengthwise of the shaft. Fritz, in U.S. Pat. No. 1,095,839, and Newton et al., in U.S. Pat. No. 2,406,891 show split rings in spaced relation in grooves on the shaft for preventing longitudinal movement of the element along the shaft.
In Osborne, U.S. Pat. No. 2,066,482, a clutch mechanism of the synchronizing type is shown for connecting the gear 8 to the shaft 3 or for connecting the driving and driven shafts together for direct drive, splines being employed for this purpose. Retainer or abutment rings are provided to hold the gear against longitudinal movement on the shaft with a locking key 25 engageable with the rings. No overload release clutch is shown nor such a clutch with few parts.
In U.S. Pat. No. 3,061,386 a tolerance ring is described comprising a corrugated elastic shim or expansion sleeve in which each corrugation acts as a compression spring to create a frictional grip on the parts it contacts. Such devices have been employed to secure synthetic plastic devices which may lack dimensional stability, distortion during curing and imcompatible thermal expansion rates, to shafts. Such devices have also been employed to mount anti-friction bearings in stamped or drawn sheet metal housings and in die cast housings, and to mount knobs to levers.
None of the prior art devices heretofore available show a slip clutch in which the pressure is applied in a comparable manner by using a tolerance ring for that purpose nor for inexpensively and economically constructing a slip clutch which only requires three relatively simple parts.